Signal source
Signal source module aims to deliver I/Q data for demodulator. There are numerous supported signal sources. For each type of the source there are provided controls for parameters tuning.
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Recorded I/Q files - you can choose a file with recorded signal - check I/Q files format. If center frequency of the I/Q file is not the PW-Sat2 center frequency, there is a frequency offset field (in Hz) where you can specify the actual offset:
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Funcube Dongle Pro+ - the device has to be accessible from normal user - follow the guide
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RTL-SDR - to use RTL-SDR with PW-Sat2 application it must be accessible from normal user.
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Pluto SDR - make sure that operating system has connected to Pluto's network adapter (especially on Debian).
- Recorded I/Q files
- RTL-SDR - follow RTL-SDR QSG to install drivers
- Audio in (SSB - USB)
In main window go to tab "Signal source", choose proper source and click "Run source". It might take a while to show window with a signal source.
There are separate settings for SDR center frequency and PW-Sat2 frequency to get rid of DC spike. Since rest of the software (i.e. Demodulator) expects PW-Sat2 signal at center frequency, Frequency Xlating FIR Filter GRC block is used in order to get rid of introduced offset.
① SDR Center Frequency (Hz) - set it lower or higher than PW-Sat2 Frequency
② PW-Sat2 Frequency (Hz) - set it to PW-Sat2 downlink frequency
③ Doppler correction (Hz) - see Doppler shift compensation
④ Center PW-Sat2 Frequency (with Doppler correction) (Hz) - it's ② + ③
⑤ Center frequency on waterfall is "Current PW-Sat2 Frequency (with Doppler correction)" - "zero" frequency on waterfall is ② + ③
Satellite signal's center frequency should be at center frequency of waterfall in signal source, like in this image:
Audio in signal source takes upper sideband demodulated signal from system audio recording device. This option is suitable for analog radio receivers with SSB-USB demodulator connected to PC via audio line in. See Audio in (SSB USB) for more details.
All signal sources (but IQ File Source) save IQ data to iq_data_from_current_session file. Saved I/Q data are after frequency correction (zero-frequency is PW-Sat2 frequency). The file is overwritten each time a signal source is launched. (IQ files spec)
If signal source cannot be launched, the reason can be found thanks to debug output. Launch the application in terminal:
cd pw-sat2-gs
./PW-Sat2_Ground_Station
and click 'Run source' to see error message/exception.
All signal sources are generated from GnuRadio Companion flow graphs, frozen by Pyinstaller and run from the main app. GnuRadio Companion flow graphs for all signal sources are available in our repository.